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Tagamet HB

Generic name: cimetidinesye-ME-ti-deen ]
Drug class: H2 antagonists

Medically reviewed by on May 20, 2024. Written by Cerner Multum.

What is Tagamet HB?

Tagamet HB is a stomach acid reducer that is used to treat and prevent certain types of stomach ulcer. This medicine is also used to treat gastroesophageal reflux disease (GERD), when stomach acid backs up into the esophagus and causes heartburn.

Over-the-counter (nonprescription) Tagamet HB is used to treat heartburn with sour stomach and acid indigestion, or to prevent these conditions when caused by certain foods or beverages.

Tagamet HB may also be used for purposes not listed in this medication guide.

Tagamet HB side effects

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning in your eyes, skin pain, red or purple skin rash that spreads and causes blistering and peeling).

Tagamet HB may cause serious side effects. Stop using Tagamet HB and call your doctor at once if you have:

Serious side effects may be more likely in older adults and those who are ill or debilitated.

Common side effects of Tagamet HB may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

Heartburn can mimic early symptoms of a heart attack. Get emergency medical help if you have chest pain that spreads to your jaw or shoulder and you feel anxious or light-headed.

You should not use Tagamet HB if you are allergic to Tagamet HB or other stomach acid reducers (such as ranitidine, famotidine, Zantac, Axid, and others)

Ask a doctor or pharmacist if Tagamet HB is safe to use if you have:

Ask a doctor before using this medicine if you are pregnant.

You should not breastfeed while using Tagamet HB.

Do not give this medicine to a child without medical advice.

How should I take Tagamet HB?

Use exactly as directed on the label, or as prescribed by your doctor.

Tagamet HB is usually taken with meals or at bedtime.

To prevent heartburn from foods or beverages, take Tagamet HB within 30 minutes before eating or drinking.

Take this medicine with a full glass of water.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

It may take up to 8 weeks for an ulcer to heal. Use this medicine for the full prescribed length of time, even if your symptoms quickly improve.

Your ulcer may take longer to heal if you smoke cigarettes.

Call your doctor if your symptoms do not improve, or if they get worse.

Do not take over-the-counter Tagamet HB for longer than 14 days without your doctor's advice.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Tagamet HB?

Avoid taking other medications within 2 hours before or 2 hours after you take Tagamet HB. This medicine can make it harder for your body to absorb certain medicines you take by mouth.

Ask your doctor before using other stomach acid reducers or antacids, and use only the type your doctor recommends.

What other drugs will affect Tagamet HB?

Ask a doctor or pharmacist before using Tagamet HB with any other medications, especially:

This list is not complete and many other drugs may affect Tagamet HB, or be made less effective when taken at the same time as this medicine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Frequently asked questions

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.